Drinking 5 Cups of Green Tea per Day May Help Reduce Blood Sugar and Gut Inflammation, New Study Suggests

Apparently, your good gut bacteria really dig it when you go green.

Beyond being tasty to drink and cozy to hold (well, when we're not in the middle of a heat wave), a mug of tea delivers a great dose of health benefits. From reducing the risk for cancer and helping manage diabetes to improving sleep and boosting creativity, there are several proven reasons to brew a big batch each morning. (We love this habit as a little 5-minute self-care ritual to kick off the day in Zen style.)

Pictured Recipe: Soothing Ginger-Lemon Tea

As of June 2022, when study results were published in the journal Current Developments in Nutrition, we have another reason to keep calm and sip on. Thanks to green tea's anti-inflammatory properties, consuming green tea was shown to reduce blood sugar levels and decrease gut inflammation and permeability. The latter is one factor involved in "leaky gut syndrome," which is based on the concept that a hyperpermeable gut can allow toxins or unwanted substances into the bloodstream.

What This Green Tea Study Found

Researchers from Pennsylvania State University and Ohio State University were curious if green tea extract might help lower the risk for the health factors related to metabolic syndrome—a group of conditions that often occur together and increase the risk for heart disease, diabetes, stroke and more. The more "boxes" of metabolic syndrome risk factors you can check, the greater the chances are that you'll develop serious health problems later in life, the Mayo Clinic explains. Here are four of the main conditions associated with metabolic syndrome:

  • Blood pressure over 130/85 mmHg
  • Excess body fat around the waist; defined by some as a waist circumference of more than 38 inches in men and more than 32 inches in women
  • Fasting blood sugar of 100 mg/dL or more or an A1C reading of 5.7% or more.
  • Fasting triglyceride levels above 150 mg/dL, fasting high-density lipoprotein (HDL, the "good" kind) cholesterol of less than 40 mg/dL for men or 50 mg/dL for women

About 35% of all American adults and 50% of Americans age 60 or older meet the mark to be diagnosed with metabolic syndrome, according to a May 2015 report in JAMA Network.

So for this study, Richard Bruno, Ph.D., senior study author and professor of human nutrition at The Ohio State University, and his team wanted to dive deeper into his research passion area for the past 15 years—green tea—to see how it might impact cardiometabolic health and explore the link to gut health, something he had previously noticed among mice.

Bruno and his team tapped 40 participants; 21 fit the criteria for metabolic syndrome and 19 didn't. Each was given gummies that contained catechins (natural polyphenolic phytochemicals found in tea, beans, red wine, strawberries and select other plants). The amount of catechins in each gummy was equal to what's found in five cups of green tea. The individuals were instructed to consume one gummy per day for 28 days. They took a month's break, and each person popped a placebo for the following 28 days.

Soothing Ginger-Lemon Tea

Throughout the course of the research, the individuals were coached to eat a diet low in polyphenols since green tea is rich in it, and they didn't want to skew the study results (if, say, one person ate an impressive amount of berries, apples and grapes).

Before the study began as well as on day 14 and 28 of both the gummy intervention phase and the placebo phase, scientists measured fasting blood glucose, insulin, lipids (cholesterol) and dietary polyphenol levels of each participant. They also asked for stool samples to study intestinal inflammation.

The result: Green tea extract was shown to lower blood sugar while reducing gut inflammation and permeability among people with metabolic syndrome and those without.

"The importance of gut health for humans is exemplified by our research and suggests that dietary factors such as green tea that are rich in catechins can help to reduce the risk of glucose intolerance by limiting gut inflammation and improving gut integrity," Bruno tells Medical News Today. "Our work shows that regular green tea consumption has the potential to be part of the solution to manage the risk of metabolic syndrome."

Next, Bruno and other researchers are hoping to dive more into how green tea affects the microorganisms in the gut to hopefully discover if green tea can boost good bacteria while helping to decrease the amount of not-so-beneficial bugs in the gut.

The Bottom Line

This new green tea study found that consuming catechins from green tea extract—to the tune of what you'd sip in about five cups of green tea—can decrease blood sugar and increase gut health.

It's worth noting, however, that this finding was from using an extract, not green tea itself. More research is needed to determine if we could steer clear of the supplement aisle and still score the gut health, chronic inflammation and blood sugar benefits by drinking five cups of tea.

Oh yes, and five cups of tea admittedly is a lot. Drinking too much caffeinated tea might lead to nausea, heartburn, jittery feelings or difficulty sleeping, so it's best to stick with decaf and work your way up. Even one glass per day, in tandem with a well-balanced whole foods-rich diet, will be a boon to your good gut bacteria, blood sugar and body as a whole.

If you'd like to make it easier to ease up from zero cups to a few more, try:

  • Ordering it iced (coffee shops often sell it in 16 ounces; equal to 2 cups)
  • Infusing green tea with herbs, citrus or ginger
  • Adding green tea to smoothies
  • Toting it around in an eye-catching infusion bottle that will remind you to drink

Beyond what you drink, what you eat matters a lot, too. In conjunction with your green tea-sipping, fill your cart with these best foods to fight inflammation and the best foods for gut health. If you'd like some more coaching, our 7-day whole food meal plan is a great start—as is individualized guidance from your primary care doctor and a registered dietitian.

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